Most of the time I just booked hotels and cancelled it later or even made some fantasy plan.
The problem is, how much of a "fantasy" are they prepared to accept? If I am wanting to fly into Chengdu for instance and out of, say, Hong Kong across 3 weeks, I am going to have to "book" up to 21 nights at hotels which get me, in a "practical" way in terms of means of transport, between the 2 cities. At the very "simplest" I could book 12 in Chengdu and 9 in Guangzhou and say I am going to fly between the 2 cities - but wouldn't they then want to see an internal flight booking - which i wouldnt of course have?
An alternative is to work out a "practical" direct route between the 2 cities using bus and rail with NO overnight transport across a minimum number of travel days (to minimize the number of separate hotel bookings) and book a hotel at each of the fictional overnight cities! Are they really going to believe that i am going to stay for say 5 nights at some "medium interest" city en route AND will actually obtain bus and train tickets exactly as planned!!!??